Apparatus for angularly relating members on a shaft



July 6, 1965 H. M. TOMASKO ETAL 3,192,639

APPARATUS FOR ANGULARLY RELATING MEMBERS ON A SHAFT Original Filed Jan.20. 1960 3 Sheets-Sheet 1 g Paar" llllllllllllllllllllll 77 v in If 60:37

INVENTOR vIPaazswr A Mu How/m0 M TOMASKO i' ATTORNEY July 6, 1965 H. M.TOMASKO ETAL v 3,192,639

APPARATUS FOR ANGULARLY RELATING MEMBERS ON A SHAFT Original Filed Jan.20. 1960 3 Sheets-Sheet 2 .--j /g INVENTOR ROBERT A. HILL /7 WARD M7'oM/qsko BY MMELMM ATTORNEY July 6, 1965 H. M. TOMASKO ETAL 3,192,639

APPARATUS FOR ANGULARLY RELATING MEMBERS ON A SHAFT 3 Sheets-Sheet 3Original Filed Jan. 20. 1960 1Z3 INVENTOR Ross/Pr A. fi u OWARD MEM/wkoBY MWLQAGIH ATTORNEY United States I Patent Claims. or. ss is2 This is adivision of our previously filed application Serial No. 3,551, filedJanuary 20, 1966, for Pretimed Three Lobed Rotary Pump.

This invention relates to an improvement in apparatus for angularlyrelating members on a shaft and deals particularly with an apparatus formounting a gear in proper predetermined relation to a rotor lobe on acommon shaft.

In the production of rotary pumps of the type described, considerabletime and efiort is required to properly locate the gears on the shafts.Due to the fact that the lobes on the pump interengage with but slightclearance therebetween, it is necessary to position the intermeshinggears on the rotor shafts with extreme accuracy. In the past, it hasbeen usual practice to mount the rotors on suitable fixtures, to key thegear on one of the shafts, and to then key the intermeshing gear to theother shaft through the use of a split key or some other arrangement tocompensate for variations in the location of the keyway in the shaft andthe location of the keyway in the gear. Properly timing the gearsrelative to the rotors has usually required from six to twenty hours ofmanual labor. It is an object of the present invention to provide a pumpof the type described having the gears properly related to the rotorsbefore the pump is assembled.

As will be understood, the lobes of one rotor are separated by valleysto accommodate the lobe of the cooperating rotor. As long as the gearson both rotor shafts have the same number of gear teeth,'the two rotorswill operate in unison. We have found, however, that by properlychoosing the gears, and by securing each gear to the rotor shaft so thatthe center of a gear tooth is directly aligned with the center of therotor lobe, the rotors and their gears may be pretimed. Obviously thesame result can be accomplished by centering a gear tooth space (midwaybetween the gear teeth) with the center of a gear lobe. To do this twothings are necessary. In the first place, it is necessary that thenumber of teeth on the gears be a multiple of the number of lobes.Secondly, it is necessary that, midway of the angular distance betweenthe lobes, the gear must have a gear tooth space, when the gear teethare centered with the rotor lobes or a gear tooth when the lobes arecentered with a gear tooth space. To simplify this description, thegears will be described as having teeth centered with the rotor lobes,although the opposite could be true.

To better describe the invention, we can consider a three-lobed pump,driven by intermeshing gears. The gears have teeth centered with eachrotor lobe, meeting the first requirement mentioned above. To center thelobe of one rotor with the valley of the other rotor, each gear musthave a tooth space angularly centered be- EJ923639 Patented July 6, 1965tween the teeth aligned with the lobes. In other words, with athree-lobed rotor, the gears must have an odd number of teeth, as gearswith an even number of teeth would provide a gear tooth midway betweenthe gear teeth aligned with the lobes.

From this description, we have worked out the formula:

where N equals the number of gear teeth, M represents an arbitrarymultiple or whole number, and L represents the number of lobes.Considering L to constitute an arbitrary multiple such as five, thenumber of gear teeth N on the gears would be five times six, plus orminus three; or thirty, plus or minus three; equaling thirtythree ortwenty-seven teeth. The same formula can be used, regardless of thenumber of lobes on the pump.

Obviously, the value of M must be selected so that the number of gearteeth on the gears is sufficient to cause the gears to properly rotate,and the teeth large enough to withstand the loads imposed by the rotorswhen pumping.

A feature of the present invention resides in the fact that by locatingeach of the gears in the same relation to the rotors, the rotor shaftand gear assemblies are interchangeable and replaceable. In the past, ifit were necessary to replace a rotor, the lobes of the rotor and theteeth of the gear had to be properly timed to properly engage theremaining rotor. By aligning one of the teeth of the gear with each ofthe rotor lobes, this difficulty is obviated.

A feature of the present invention resides in a novel method of aligningthe gears with the rotors. Considering a three lobed rotor, a jig isprovided including a supporting surface on which the rotor is supportedwith two of the three lobes resting against the surface and with therotor shaft engaged in generally U-shaped fittings. The center of thethird lobe of the rotor is then on a plane through the axis of the rotorperpendicular to the supporting surfaces. The gear is mounted on therotor shaft in the correct axial location and a tooth space on thebottom of the gear is engaged with a toothshaped projection fixed on apart of the jig which is movable vertically but fixed from axial ortangential movement. A tooth on the top of the gear is, at the sametime, engaged in a notch in a locating arm, and which is movableparallel to the rotor support and cooperable with an indicating gauge to:show if the gear has been properly centered relative to the rotor.

These and other objects and novel features of the present invention willbe more clearly and fully set forth in the following specification andclaims.

In the drawings forming a part of the specification:

FIGURE 1 is a vertical sectional view of those portions of a rotary pumpnecessary to an understanding of this invention showing pertinentfeatures of the general form of construction thereof.

FIGURE 2 is a cross sectional view of the pumpshown in FIGURE 1, theposition of the section being indicated by the line 22 of FIGURE 1.

FIGURES diagrammatically illustrates the ends of a pair of rotors andthe gears onthe rotor shafts, showing'the relationship between the lobesand the gears.

FIGURE 4 is a front elevational view of a jig employed to properlylocate the gears relative to the rotors.

FIGURE 5 is an end elevational view of the jig shown in FIGURE 4.

FIGURE 6 is an end elevational view of the jig, the view showing the endof the jig opposite that shown in FIGURE 5.

FIGURE 7 is a top plan view of the jig.

The structural features of the pump and the manner of operation thereofare set forth in detail in our pre viously mentioned application SerialNo. 3,555.

However, in order to describe briefly the structural features of thepump structure necessary to an understanding of this invention, therotary pump is indicated in general by the letter A. The pump includes ahousing 10 having upper and lower arcuate portions 11 and 12 which formintersecting rotor chambers 13 and 14 designed to accommodate threelobed rotors 15 and 16 respectively. The rotors 15 and 16 are mountedupon supporting shafts 17 and 19 respectively. As is usual in pumps ofthis type, the lobes of the rotors engage in the hollow portions betweenthe lobes of the cooperating rotor to provide a minimum of leakagebetween the two rotors.

The housing 10 includes an inlet passage 20 and an outlet passage 21incommunication with the rotor chambers 13 and 14. The fluid being pumpedenters. the inlet 20, is carried between the rotor lobes and the arcuatewalls 11 and 12 and are discharged through the discharge passage 21.

The ends of the housing 10 are closed at both ends by end plates 25which are properly located by dowel pins 26 i which extend through theend plates and into the housing 10. Bearing supporting plates 49 aresecured in face contact with the end plates 25 and are also locatedrelative to the end plates and the pump housing by suitable means suchas by the dowel pins 26. The bearing sup porting plates 27 are aperturedto accommodate a pair of sealed bearings 28. Seals and grooves 29 areused to seal the outer races of the bearings 28 relative to the walls ofthe apertures 29. The inner races of the bearings may be'sealed relativeto the shaft 17.

The bearing supporting plates 27 are also provided with a second pair ofaligned apertures 52 which support sealed bearings 54 which support theshaft 19. The outer races of the bearings 54 are sealed relative to theapertures 52 by seals and grooves 56. A relief valve assembly isgenerally indicated at 57.

Gears 77and 79 are pinned to the shafts 17 and 19 respectively by pairsof taper pins 80 and 81 extending a diametrically to apertures 82 and 83in axially spaced relation in the gears 77 and 79. The gears 77 and 79are provided with angularly spaced teeth 84 and 85, the number of whichis odd and divisible by three. In the particular arrangement illustratedin FIGURE 3 of the drawings, the gears 77 and 79 have 27 teeth. One ofthe teeth 84 is directly aligned with the center of each lobe of therotor 15, and one of the teeth 85 is exactly aligned with the center ofeach of the lobes of the rotor 16, and a gear tooth space is centeredbetween adjacent lobes. In view of this fact, the rotors are pretimed sothat upon insertion of the rotors into the pump so that a lobe of onerotor extends into the valley between the lobes of the other rotor, theteeth of the two gears will be automatically in mesh.

In the past, considerable time and effort have been required to properlytime the rotors and gears so that the rotors will fit properly togetheras the gears rotate. A variation of a few thousandths of an inch in theposition of a key or keyway greatly affects the operation of the pump orrenders it inoperative. Any small variation in the location of a key orkeyway causes a considerably greater variation at the outer diameter ofthe gear or rotor. As a result, a time of from six to twenty hours hasbeen considered the usual time required to properly time the rotors andgears. In the present method which will be described, the same operationcan be completed in perhaps thirty minutes with accuracy virtuallyguaranteed.

In FIGURES 4 through 7 of the drawings a jig is disclosed which properlylocates the gears in pretimed relation to the lobes of the pump rotor.This jig includes a supporting base 89 on which are mounted flat toppedsurface blocks 90 and 91 having their upper surfaces on a common plane.The blocks 90 and 91 are held in place on the top of the base 89 by anysuitable means such as by the bolts 92 and 93. A shaft positioning block94 is secured on the base 89 by bolts 95 or other suitable means and agenerally similar shaft positioning block 96 is supported on the base 89at the opposite sides of the blocks 90 and 91 and heldin place by bolts97 or other suitable means. As indicated in FIGURE 6 of the drawings,the upper end of each of the shaft positioning blocks 94 and 96 includesa central notch 99 having parallel shaft engaging surfaces 100 on theinner surface thereof. These surfaces 100 are accurately ground ormilled to fit portions of the rotor supporting shafts 17 and 19 and thesurfaces of the two blocks 94 and 96 are accurately aligned so as tohold the shaft engaged therein from any transverse movement.

The shaft guide block 96 is provided with a projecting ground surface101 againstwhich the end of a rotor such as 15 may engage. The oppositeside of the block 96 is provided with a parallel flat surface 102 whichis engage able with a surface. of a gear such as the gear 77. 'When therotor engages the surface 101 and the gear engages the surface 102, thetwo elements are properly axially spaced.

A clamping arm 103 is pivotally supported between a pair of ribs 104 onthe base 89 by means of a pivot 105. As indicated in FIGURE 5 of thedrawings, the clamping arm 103 is provided with a bifurcated end 106through which the rotor shaft 17 may extend. Opposed ground surfaces 107properly locate the shaft relative to the clamping arm. As indicated inFIGURE 4 of the drawings, each side of the bifurcated end 106 isprovided with a laterally extending rounded projection 109 designed tobear against the gear 77. A clamping bolt 110 having a head 111 extendsthrough the clamping arm 103 and into the base 89 to clamp the roundedprojections 109 against the gear.

A means is provided for properly indexing the gears such as 77 relativeto the rotor 15. A plunger 112 is slidably supported in a vertical bore113'having its axis in a vertical plane through the axis of the rotorshaft 17. A head 114 is provided on the upper end of the plunger 113 andan upwardly extending lug 115 having a tapered upper extremity 116 whichis shaped similar to the teeth of the gear 77 is mounted on top of thehead 114. The plung r 112 is raised and lowered by means of a drivingplunger 117 which is slid-able in a vertical bore 119 coaxial with thebore 113. The driving plunger 117 is provided with a tapered notch 120which is designed to receive the frusto-conical end 121 of a threadedshaft 122. The shaft 122 is threaded into the base- 89 and is providedwith a hand wheel 123 by means of which the threaded pin or shaft 122may be rotated. A pin 124 is slidably supported in an internallythreaded passage 125 which intercepts the axis of the plunger 117 andthe pin includes. an end 126 which is slidably engaged in a slot 127extending longitudinally of the plunger 117. The pin 124 is held inplace by a set screw 129 and acts to limit the slidable movement of thepushing plunger 117 and also to prevent this plunger from rotation inthe bore 119.

An arm 130 is pivotally and slid-ably connected by a pivot 131 to abracket 138 mounted on the upper surface of the base 89. The arm 130 isprovided with a projection 132 including a notch 133 which is shapedsimilarly to the shape of the gear teeth. The pivot 131 extends througha slot 134 which is elongated longitudinally of the arm 130 so that thearm 13! may move horizontally within the limits of the slot 134. A gauge135 is mounted upon a bracket 136 attached to the bracket 13% andincludes a plunger 137 which may be moved longitudinally of the sleeve139. The gauge 135 indicates the position of the plunger 137 which abutsagainst the end 14% of the arm 13! for a purpose which will bedescribed. 7

In operation, the rotor 15 which is fixedly mounted upon the shaft 17 isplaced upon the ground upper surfaces of the blocks 99 and 91 with twoof the three lobes of the rotor resting upon the horizontal uppersurfaces of these blocks. The shaft 17 is properly located between theground surfaces ltltl of the shaft positioning block 94 and anintermediate portion of the shaft 17 is properly located between similarground surfaces of the shaft positioning block 96. The end of the rotor15 is moved into contact with the locating surface 101. As is indicatedin FIGURE 6 of the drawings, a block 143 is mounted upon the base 89 toone side of the blocks which support the rotor 15. A stud 144 isthreaded into the top of the block 143 and is held in adjusted relationby means of a lock nut 145. The stud 1 54 is provided with an axiallyextending pin 146 which is engageable in a slot 147 in the under surfaceof a clamping bar 14-9. The clamping bar 149 extends over the centerline of the rotor shaft supports. A threaded stud 150 also extends intothe block 143, the axes of the studs 144 and 150 being at right anglesto the axis of the rotor shaft. A locking nut 151 holds the stud 150 ata proper elevation. A spring 152 encircles the stud 150 above the nut151 and supports a washer 153. The stud 150 extends through a slottedaperture 154- in the clamping block 149 and a clamping nut 155 isprovided on the end of the stud by means of which the clamping bar 149may be clamped against the uppermost lobe of the rotor 15, the pin 146serving as a fulcrum point. The clamping bar 149 will clamp the rotor 15firmly in place with the center of the uppermost lobe of the rotor on avertical plane through the axis of the shaft.

The gear 77 is next manually moved against the bearing surface 102 andthe plunger 112 is raised by threading the threaded pin or shaft 122into the notch 126, the frusto-conical end of the shaft acting as a camagainst the upper surface of the notch 120. When the wedge-shapedprojection 116 on the plunger head 114 is properly engaged in the spacebetween two of the gear teeth 84, one tooth at the top of the gear 77will be centered on the vertical plane through the rotor shaft 17 andthrough the center of the uppermost lobe of the rotor.

When the gear is properly located, the arm 13% is pivoted down from thedotted line position illustrated in FIG- URE 5 of the drawings to gearengaging poistion shown in full lines in this figure. The arm 1 34 maymove horizontally within the limits of the groove 134, any such lateralmovement moving the plunger 137 of the gage 135. If the gear 77 isexactly in the proper location, the gauge 135 will so indicate, thegauge being set to provide a predetermined zero reading when the arm 130is in proper position. If the gear 77 is not exactly in position, thetooth engaged in the notch 133 will be too near or too far from theplunger 137 and the gauge will so indicate.

The clamping arm 103 may then be tightened against the gear 77 to holdthe gear against the surface N2. If preferred, this clamping arm may betightened prior to the testing of the gear position by the arm 13%. Oncethe clamping bar 149 and the clamping arm 103 are tightened, holes maybe drilled in axially spaced relation through the gear 77 and shaft 17,these holes being indicated at 82 in FIGURE 1 of the drawings. The holes82 are reamed or otherwise cut to a tapered form and undercut at one endas indicated at 157 to accommodate the taper pin 86. This undercuttingis done prior to the assembly procedure.

It will be seen that by selecting gears 77 and 79 with spaced peripheralteeth which are in multiples of three, three teeth of each gear will beproperly aligned with the the rotor lobes.

center line of the three corresponding rotor lobes. By choosing thesegears with an odd number of teeth, a tooth space is provided inalignment with each valley between Thus, in assembling the pump, thelobes of the rotors may be readily arranged in properly timed relationthrough the meshing of the gears 77 and 79. Obviously, the gear 79 ismounted upon the rotor shaft 19 in properly timed relation with therotor 16 in the manner described, the rotor shafts being identicalexcept for the difference in length. By the use of the fixture, thegears may be pinned to the rotor shaft in a relatively few minutes,effectively accomplishing a result which previously required from six totwenty hours of labor. Furthermore, should it ever become necessary toreplace a pump rotor, the new rotor may be inserted in place of therotor removed and will automatically be in proper time as long as theproper teeth of the meshing gears are engaged.

In FIGURE 2 of the drawings a groove 159 is shown in the end plate 25forming an end Wall of the pump. A similar groove is provided in theother end plate. These grooves lead from the discharge side of the pumpto the seal chambers, subjecting these chambers substantially todischarge pressure. rubs against the end plate the clearance at that endwill be reduced to zero and the pressure in the seal chamber will besubstantially equal to discharge pressure. At the other end, however,the clearance between the rotor and the end plate will increase to amaximum, allowing liquid to bleed readily from the seal chamber to thesuction side of the pump, reducing the pressure in the seal chamber tosomewhat below discharge pressure. This results in an end thrust tendingto move the rotor to central position where it has equal clearance witheach end plate.

In accordance with the patent statutes, we have described the principlesof construction and operation of our improvement in apparatus forangularly relating members on a shaft, and while we have endeavored toset forth the best embodiment thereof, we desire to have it understoodthat changes may be made within the scope of the following claimsWithout departing from the spirit of our invention.

We claim:

1. An apparatus for properly angularly relating a three lobed pump rotorhaving a rotor shaft coaxial therewith and fixed thereto with a gearrotatably supported on the shaft, the apparatus including a flat surfaceon which two of the three rotor lobes are adapted to rest, meanspositioning the rotor shaft with its axis parallel to said flat surface,means adapted for clamping said rotor against said surface with said twolobes resting thereon, and plunger means supported for movement on anaxis normal to said flat surface and including an end for engagementwith said gear to hold said gear with the teeth of the gear in fixedangular relation to said rotor lobes.

2. An apparatus for angularly relating one of the rotors of a rotarypump having a pair of identical lobed rotors, shafts coaxial with andsupporting said rotors, and gears on said shafts and intermeshing todrive said rotors in unison with the gear mounted on said one rotor, theapparatus'including a supporting table on which said one rotor isadapted to rest, the table being adapted for engagement with two of thethree angularly spaced rotor lobes to hold said lobes in fixed relationthereto, means adapted for engagement with said shaft above said tableadapted for holding said rotor in a predetermined position on said tablewith the shaft axis parallel to the table, means for clamping said rotoragainst said table, and means extending perpendicularly relative to saidtable and in alignment with said means adapted for engagement with saidshaft and midway between said two lobes when resting on said tableadapted to engage with said gear on said shaft to hold said gear withits teeth in a predetermined angular position relative to said shaft andto the if the rotor moves axially until it p 6 rotor lobes, whereby saidgear may be secured to the rotor shaft in fixed relation to the rotorlobes.

3. The structure of claim 2 and in which said means engageable with agear comprises means capable of engaging between two adjacent teeth onsaid gear.

4. The structure of claim 2 and including means adapted to engage withsaid gear when resting on said table and movable in a plane normal tothe axis of the rotor shaft, and indicating means actuated by said lastnamed means are properly angularly related to the lobes thereof.

5. The structure of claim 2 and in which said shaft means adapted forengagement with said shaft comprises a pair of bracket members extendingupwardly from said table and having aligned notches in the upper endsthereof in which said shaft is adapted to engage.

No references cited.

ISAAC LISANN, Primary Examiner.

1. AN APPARATUS FOR PROPERLY ANGULARLY RELATING A THREE LOBED PUMP ROTORHAVING A ROTOR SHAFT COAXIAL THEREWITH AND FIXED THERETO WITH A GEARROTATABLY SUPPORTED ON THE SHAFT, THE APPARATUS INCLUDING A FLAT SURFACEON WHICH TWO OF THE THREE ROTOR LOBES ARE ADAPTED TO REST, MEANSPOSITIONING THE ROTOR SHAFT WITH ITS AXIS PARALLEL TO SAID FLAT SURFACE,MEANS ADAPTED FOR CLAMPING SAID ROTOR AGAINST SAID SURFACE WITH SAID TWOLOBES RESTING THEREON, AND PLUNGER MEANS SUPPORTED FOR MOVEMENT ON ANAXIS NORMAL TO SAID FLAT SURFACE AND INCLUDING AN END FOR ENGAGEMENTWITH SAID GEAR TO HOLD SAID GEAR WITH THE TEETH OF THE GEAR IN FIXEDANGULAR RELATION TO SAID ROTOR LOBES.